The invention relates generally to signal processing, and more particularly to systems and methods used in the transformation of image signals between the analog and digital domains to aid in image signal processing.
Signal processing is a valuable tool for various applications that involve data transmission, data storage, and the like. One aspect of signal processing, for certain applications, is to convert an analog signal into its digital equivalent to facilitate storage, transmission, workability, signal conditioning, noise filtering, and the like. For example, a digital X-ray panel may convert a scanned X-ray image into a digital format for subsequent processing, storage and image reconstruction.
Various signal processing techniques exist that provide transformation of image signals between the analog and digital domains. One such method for performing analog-to-digital (A/D) signal conversion utilizes a single digital-to-analog converter (DAC) for providing a base analog signal for comparison to an input analog signal that requires conversion.
Although such a method provides high accuracy, one disadvantage with A/D conversion using a single DAC is that the process is slow. This is because each input analog signal is converted individually into a digital equivalent by a dedicated channel, and all the channels are driven by the same DAC. The counter that provides a digital count to the DAC, therefore, has to run from the lowest count to the highest count before all channels perform conversion of each input analog signal into digital equivalents.
Attempts have been made to increase the speed of A/D conversion process. One method of increasing the speed is by increasing the number of DACs so that each channel has a dedicated DAC. However, such a method may not be cost effective in certain applications. For example, a digital X-ray panel using a single DAC for A/D conversion process has a speed of 30 frames per second (fps), which may not be suitable for applications requiring higher frame rate. The speed may be improved by increasing the number of DACs. However, due to the increase in cost and complexity of the additional circuitry, such a digital X-ray panel becomes prohibitively expensive and complex.
There is therefore a need for a system and method to improve the speed of A/D conversion process.